Method and insulation for heating devices



J. J. ZWERLING.

METHOD AND INSULATION FOR HEATING DEVICES.

APPLICATION FILED MAY 20, 1920.

Patented Dec. 1920.

2 SHEET ET I.

ZJIQZEYJNTOR. BY 9 Jog :1

A TTORNEYS.

J. J. ZWERLING.

METHOD AND INSULATION FOR HEATING'DEVICES.

APPLICATION FILED MAY 20, 1920.

1,363,074. Patentd Dec 21,1920.

2 SHEETSSHEET 2.

A TTORNEYS.

PATENT OFFICE.

JOHN J'. ZWERLING, OF SAN FRANCISCO, CALIFORNIA.

METHOD AND INSULATION FOR HEATING DEVICES.

Application filed May 20, 1920.

T 0 all whom it may concern:

I Be it known that 1, JOHN J ZWERLING, a citizen of the Republic of Austria, and a resident of the city and county of San Fran cisco, State of California, have invented new and useful Improvements in Methods and I-nsulations for Heating Devices, of which the following is a specification.

My invention has for its object the formation of a coating for metallic surfaces, which coating possesses permanence under high temperatures and under all conditions of temperature high electrical resistance. and is free from deterioration either chemical or mechanical throughout temperature ranges in excess of those normally met with in electrical heating devices.

Another object is to secure more eiiicient heat conductivity between the heat generating element and the metallic surfaces from which it is insulated and which the said element is adapted to heat, thereby securing quicker and more effective heat transmission from the element to the metal.

Other objects will appear from the description which follows.

This object I attain by applying to the metallic surface which it is desired to insu late a solution of sodium silicate containing an inert material, as silica or carborundum, or any substance of similar nature having high resistance, and which is to be mixed with the sodium silicate solution to a creamy consistence. This is then applied to the me tallic surface preferably with a brush or by spraying, and substantially at room temperatures. On this primary coating T sprinkle coarsely ground inert material, as quartz sand, or other similar material, such that the wet surface of the primary coat forms a binder for the said granular second coat. The layer so formed is now dried, and for this purpose an oven temperature of 150 degrees will be found advantageous, and the surface so formed is ready for use in heating devices.

Although I have described but one primary coat of silicate mixture and one sec ondary coat of granular inert material, may at times be advantageous to apply other coats of silicate and the dry inert material, thus building up to any desired degree an increased thickness of completed coating, although for most devices T have found the single coat of silicate mixture and the coat of inert material to be sufficient.

Specification of Letters Patent.

Patented Dec. 21, 1920.

Serial No. 382,844.

By referring to the accompanying drawings my invention and its application to electrical devices will be made clear.

Figure 1 illustrates the well known form of an electric iron, to which my invention is particularly adapted.

Fig. 2 is a vertical cross section through the base and heating element and certain interior parts of such an iron as in Fig. 1.

Fig. 3 is a plan view of the base of the iron to which my insulation has been applied and on top'of which has been super imposed the heating element.

Fig. 4 is an alternate form of heating element applicable to a metallic surface protected with my insulation.

Fig. 5 is a cross section through the base ofan iron such as illustrated in Fig. 3, in which a different type of heating element is employed and showing the application of my insulation where such form of heating element is employed.

Throughout the figures like numerals refer to like parts.

Referring particularly to Figs. 1 and 2 the numeral 1 indicates the base portion of an electric iron, the heating elements and interior parts of which are inclosed in a cover housing 2, and the structure provided with a handle as 3. Terminals for connecting, energizing electric circuit are shown at 4 and 5, suitably insulated as at 6 and 7, from the casing or cover 2. At 8 is shown a mass of suitable metal or heat retaining substance, and at 9 and 10 respectively are shown layers of my insulation between which is' located the heating element 11.

The heating element here shown in 3, consists of a piece of thin conducting material punched to give a resistance path to the flow of electric current, which is to be insulated from contact with the metal parts of the iron structure as by my insulation 9.

The surface of the base, Fig. 3, T provide with a coating of my insulating material, as shown at 9, and then place the heating element ll thereon, thereafter superimposing the upper element 8 (see Fig. 2) to which a similar coating of insulating material, as 10, has been previously applied.

The two parts are now to be clamped together as by screws, not shown, but to be inserted in the holes 12, 13, in the well known way and by which the parts are securely clamped together retaining the wafer-like heating element 11 in contact between the by a layer of insulating material formed by base and the upper part 8, but securely insulated therefrom by the layer of insulation on each side of the heating element.

The main leads or terminals 4, 5 are then connected at 14, 15 respectively, and other parts assembled, and the iron is ready for use by connecting the energizing electric circuit to the terminals 4, 5.

At Fig. 4c is shown an alternate type of heating unit which consists of a band, or ribbon, of conducting material, as 16, which may be wound upon an insulated member, as mica, or the like, at 17. The entire heating element assembled on its mica frame, and of suitable dimensions, may then be assembled in the same manner as described for the heating unit 11, mentioned above; The metallic portions of the heating units, in both cases, may be permitted to contact directly with the layers of my insulating material above described, and which T have found particularly advantageous for this class of service. I

At Fig. 5 is shown an alternate construe tion of heating unit and base wherein the heating elements are shown at l8, 19, 2 0 and 21, as bedded in cement material 22, 23. The manner of construction is preferably that of coating the inner surface of the iron with layers of my insulation material as at 2%, 25, and then inserting helically wound heating elements 18, 19, 20, 21, in the compartments thus formed and then casting around them a suitable cement as 22, 23.

Tn constructions employing my invention for insulating the electrical heating unit from the metallic base, or other structure, it is to be noted that the closest possible contact consistent with adequate insulation is attained, thus securing more efficient heat transmission and therefore the quicker heating er that portion of the structure which it is desired to heat. ldoreover, a much cheaper form of element may be employed as that of the helically wound elements illustrated in cross section in ll ig. 5, and the flat element of Figs. 2 and 3 ascontrasted with the more expensive form indicated in Fig. a.

T claim:

1. The method of insulating metallic parts applying to said parts a coating composed of a solution of sodium silicate having in suspension inert material in finely divided form and thereafter impregnating said coating with further inert material in a granular form and which adheres to said coating.

2. The method of insulating metallic parts by a layer of insulating material formed by applying to said parts a coating composed of a solution of sodium silicate having in suspension inert material in finely divided form and thereafter impregnating said coating with further inert material in a granular form and which adheres to said coating, and then drying the layer of insulating material so formed.

3. Electrical heating devices comprising an electrical resistance interposed between layers of insulated material which is formed on the surfaces of the parts adapted to be heated, said layers consisting oi a sodium silicate solution carrying inert material on which has been distributed relatively coarser inert material.

4. Tn an electric iron a metallic base meinber coated on its upper surface with sodium silicate solution carrying finel divided inert material on which has been applied a coarser ground inert material.

Tn an electric iron, a base member as set forth in claim a, and an electrical resistance imposed on said surface coating.

6. ln electric iron, a base member as set forth in claim l, an upper member having its lower surface coated in the same manner as the base member and an electrical resistance inter )osed between the base and the upper mern er.

7. An electric iron comprising the parts set forth in claim 6, a cover adapted to house .the upper member, the resistance and a portion of the base member, a handle and'supports therefor and binding means rigidly clamping said resistance between the upper and the base members.

lln testimony whereof, T have hereunto set my hand at San Francisco, California, this 15th day of May, 1920-. 

